Use `filled` button variant for the "Duplicate entity" modal (#45218)

frontend/src/metabase/forms/components/FormSubmitButton/FormSubmitButton.tsx

@@ -44,6 +44,7 @@ export const FormSubmitButton = forwardRef(function FormSubmitButton(
       type="submit"
       color={submitColor}
       disabled={isDisabled}
+      variant="filled"
     >
       {submitLabel}
     </Button>